post swap alternator problems - Honda Prelude Forum

4thGVtec · 01-06-2005, 09:53 AM

i just finished my h22a1 -> h22a swap last week and since the swap the alternator hasnt been working. i pulled the one that origionally came with the h22a and put my usdm one on 2 days ago(that was working fine before the swap), jumped the car, but it wouldnt hold a charge. so i went and got a new battery yesterday(thank god for 3 year free replacment) and got the alternator tested on the car, and it failed.

now the catch is the one that came on the JDM block tested good. is there a specific ground that the alternator runs off of that i may have missed? i dont want to pull the usdm alternator until i've checked everything else it could be, since it was kind of a pain to do yesterday and im not looking forward to having to do it again.

tenzola · 01-06-2005, 11:10 AM

is there a reason you can't run the jdm alternator?.. is it a problem where the bracket holes don't liine up with the bolts or is the pulley differant?

how old is the usdm one? there's not a lot that can go wrong with an alternator because there aren't that many parts.. but there are parts that wear down after time.. also after a hard hit.. sometimes that can cause a short

if i can find my notes from school i'll post up the parts that can wrong with the alternator... but in any case.. alternators just like any other moving part.. do go bad

jsmooney · 01-06-2005, 01:52 PM

i think he said that it wouldnt work, then he swapped to the usdm and it would not work either. i thought that all the alternators were the same for those motors. is the plug the same? what about the wire that bolts on there from the battery? clean the connection to the alternator plug and then come back. good luck - electrical problems are hell

4thGVtec · 01-06-2005, 09:29 PM

im going to go ahead and swap the one off the jdm block back just so i know for sure im working with a good alternator and check all the damn wires and make sure nothing got pulled or is dirty.

4thGVtec · 01-07-2005, 10:41 AM

well, before i pulled the current alternator on there i tested the wiring harness. the black/yellow one was pulling the correct voltage(12.xx), but the white/green was pulling about 0.25v. im currently chasing the wire, but on my wiring diagram it shows that its a ecu wire, but in my manual(the online honda one in pdf) its saying its connected to the PGM-FI ECM. it is looking more and more like an electrical problem....

4thGVtec · 01-08-2005, 11:38 AM

well, after going over the wiring diagram i found the white/green one going into the ecu, and found it on the car, tested it and pulled the same voltage (~0.2). it said t check the wire for an open circut, but it is nearly impossible to follow the wire once it goes into the main harness. could i possibly run a new wire from the alternator to the ecu, or is it somethihng else because it pulled the same volatage on both sides?

4thGVtec · 01-10-2005, 01:37 PM

i checked on the 2 main harnesses by the engine bay fuse box and couldnt find that white/green wire... where else could it be going through the firewall at?